CN-122000397-A - Zinc-iodine flow battery electrolyte and application thereof, and zinc-iodine flow battery

Abstract

The application discloses a neutral zinc-iodine flow battery electrolyte composition based on two-electron reaction and application thereof, and belongs to the field of flow batteries. The electrolyte adopts zinc salt, iodine salt, acetate, specific amine compounds and supporting electrolyte as main active components of the electrolyte. The amine compound used in the electrolyte can generate two-electron transfer reaction on active material iodine at the positive electrode side of the battery, and realize reversible oxidation-reduction reaction from-1-valence iodine to +1-valence iodine. Compared with the original irreversible multiple electron transfer reaction, the two-electron transfer reaction has higher reversibility, can have two reversible charge and discharge platforms, can obviously improve the energy efficiency of the battery, and is beneficial to the application of the zinc-iodine flow battery based on the multiple electron transfer reaction.

Inventors

• LI XIANFENG
• XU YUE
• XIE CONGXIN

Assignees

• 中国科学院大连化学物理研究所

Dates

Publication Date

20260508

Application Date

20241107

Claims (9)

1. 1. The zinc-iodine flow battery electrolyte is characterized by comprising iodide ions, zinc ions, acetate ions, amine compounds and supporting electrolyte.
2. 2. The zinc-iodine flow battery electrolyte according to claim 1, wherein the iodine ions in the electrolyte are provided by adding iodized salt, and the iodized salt is one or more of sodium iodide, potassium iodide, ammonium iodide, magnesium iodide and calcium iodide.
3. 3. The zinc-iodine flow battery electrolyte according to claim 1, wherein zinc ions in the electrolyte are provided by added zinc salt, and the zinc salt is one or more than two of zinc acetate, zinc sulfate, zinc iodide, zinc chloride, zinc nitrate and zinc perchlorate.
4. 4. The zinc-iodine flow battery electrolyte according to claim 1, wherein acetate ions in the electrolyte are provided by added acetate, and the acetate is one or more of sodium acetate, potassium acetate, zinc acetate, magnesium acetate and ammonium acetate.
5. 5. The zinc-iodine flow battery electrolyte according to claim 1, wherein the amine compound in the electrolyte is one or more of succinimide, sodium sulfamate, potassium sulfamate, 5-dimethyl hydantoin and sulfamide.
6. 6. The zinc-iodine flow battery electrolyte according to claim 1, wherein the supporting electrolyte is one or more of sodium sulfate, ammonium sulfate, sodium chloride, potassium chloride, sodium nitrate and potassium nitrate.
7. 7. The zinc-iodine flow battery electrolyte according to claim 1, wherein: The electrolyte is an aqueous solution; Wherein the concentration of the iodized salt is 0.01-7mol L -1 , preferably 0.4-4mol L -1 ; The zinc salt concentration is 0.1-4mol L -1 , preferably 1-2mol L -1 ; the acetate concentration is 0.1 to 3mol L -1 , preferably 0.5 to 3mol L -1 ; The concentration of the amine compound is 0.5-6mol L -1 , preferably 1-4mol L -1 ; The supporting electrolyte concentration is 0.1 to 3mol L -1 , preferably 0.3 to 2mol L -1 .
8. 8. Use of the zinc-iodine flow battery electrolyte of any one of claims 1-7 as an electrolyte in a zinc-iodine flow battery.
9. 9. A zinc-iodine flow battery, characterized in that the flow battery comprises a positive electrode, a negative electrode and a diaphragm for separating the positive electrode and the negative electrode, wherein the positive electrode is arranged in a positive electrode side cavity, the negative electrode is arranged in a negative electrode side cavity, and one or more than two of the electrolyte solutions described in any one of claims 1-7 are respectively filled or flow through the positive electrode side cavity and the negative electrode side cavity.

Description

Zinc-iodine flow battery electrolyte and application thereof, and zinc-iodine flow battery Technical Field The application relates to a zinc-iodine flow battery electrolyte and application thereof, and a zinc-iodine flow battery, belonging to the field of flow batteries. Background With the progressive consumption of fossil energy, the duty cycle of renewable energy in energy utilization becomes higher and higher. However, renewable energy sources such as wind energy and solar energy are affected by weather and have large fluctuation, and efficient grid connection is difficult to achieve. In order to solve the problem, the energy storage technology can be used for realizing peak clipping and valley filling, so that the renewable energy source is smoothly and stably output in the power grid. Among many energy storage technologies, the flow battery has the advantages of high safety, long cycle life, flexible design and the like, and is suitable for large-scale renewable energy utilization. In different flow battery energy storage technologies, the zinc-iodine flow battery has the advantages of high safety, high battery voltage, good battery dynamics, rich sources and the like, and is a good flow battery system. However, zinc-iodine flow batteries still have some problems that make them unavailable for large-scale applications. The high cost of iodine and low utilization rate of unit iodine are main problems restricting the application of iodine. Currently, conventional zinc-iodine flow batteries generally only utilize an electron transfer reaction from iodide ions to three-negative iodides, with 2/3 of the electrons being transferred to one iodine atom. However, in practice, iodine is very abundant in valence state, and +1 valence, +3 valence, +5 valence, and the like, in addition to-1 valence and 0 valence. If iodine with higher valence state can be utilized, the electron transfer number of unit iodine atoms can be effectively increased, so that the energy density of the battery and the utilization rate of iodine are improved, and the cost of the zinc-iodine battery is reduced. However, in aqueous solutions, the conversion of elemental iodine of valence 0 to iodine of a higher valence state results in the formation of irreversible iodate. The direct discharge polarization of iodate is very large, only a part of iodide ions can be generated first, then the iodate reacts with the iodate to generate an iodine simple substance, and the discharge is carried out through the iodine simple substance. As a result, only one platform exists in the discharge process, the potential difference between the charging and discharging platforms is large, so that the energy efficiency of the zinc-iodine flow battery is low, and the zinc-iodine flow battery is very unfavorable for the application in the energy storage scene. Therefore, how to improve the iodine utilization of the zinc-iodine flow battery and the reversibility of iodine in multiple electron transfer reactions is a technical problem to be solved in order to realize the application of the zinc-iodine flow battery. Disclosure of Invention In order to solve the technical problems, the invention aims to provide a reversible two-electron reaction neutral zinc-iodine flow battery electrolyte and application thereof in a flow battery. The invention adopts iodized salt, acetate and amine compound as the reaction substance on the positive electrode side in the electrolyte. The amine compound selected in the invention can generate reversible two-electron transfer reaction with iodine ions, so that the electron transfer number of unit iodine atoms is effectively improved. In the charging process, iodine ions are electrochemically oxidized to generate iodine simple substance to realize one electron transfer from-1 valence to 0 valence, and then the iodine simple substance with 0 valence is further electrochemically oxidized and reacts with amine compounds to generate iodinated amine compounds to realize one electron transfer from 0 valence to +1 valence. During the conversion from an amine compound to an iodo amine compound, a proton is released, and thus acetate is required to combine with this proton to form acetic acid, effectively buffering the pH of the solution. In the discharging process, the iodinated amine compound with +1 valence is firstly subjected to electrochemical reduction to generate an iodine simple substance, so that one electron transfer from +1 valence to 0 valence is realized, and then the iodine simple substance with 0 valence is further subjected to electrochemical reduction to generate iodine ions, so that one electron transfer from 0 valence to-1 valence is realized. The whole process is two-step two-electron transfer, and the reversibility of the reaction is good. The iodinated amine compound generated after the selected amine compound reacts with the iodine intermediate state with the valence of +1 has higher stability, and electrons can be effecti